Adding 2-stroke oil to diesel

[Cantata]

I notice several people mentioning lately they add 2-stroke oil to the diesel, to 'improve lubricity'.
I can understand why this might be a good idea. I wondered if there is some science being applied and there is a recommended dose? Or is it just a 'glug' after refueling?

 

[Lakesailor]

I haven't noticed those posts.
Diesel engines have pressure oil-feeds to the places that require an oil film, other parts get splash lubrication.
Injectors are engineered to cope with the viscocity of diesel fuel so adding oil into that can't be a good idea.
Injectors supply a measured amount of fuel to the combustion chamber. Why would it be a good idea to dilute that with lubrication oil?

Not something I would consider.

 

[jerrytug]

Quite right,diesel engines are designed to run on it,no need to add anything. However..they will also run on central heating oils,jet fuel, and suchlike,which indeed lack the 'lubricity" (slimy-ness) needed for the injector pump and nozzles. So, consider adding lube oil if you`re NOT using diesel. Obviously,ask permission from Customs and Excise before you do it cheers Jerry

 

[TQA]

Modern low sulpher diesel fuel has less lubricating oil in it than the traditional fuel blend.

The injector pump and injectors benefit from having a fuel blend with good lubricating properties.

So adding a small qty of 2 st oil to a low sulpher fuel has benefit.

A diesel engine will happily run on fuel containing up to 5% of added oil. Some operators have been doing this for many years with large fleets of vehicles and use it to burn their waste lubricating oil after filtering. They get a small benefit in terms of miles per £ and do not have to pay someone to dispose of their waste oil.

A 'glug' less than 5% is OK.

 

[Nostrodamus]

It was something I was asking about it another post and as recomended by quiet a few.
I recall Merceedes doing a big test with it.

 

[DownWest]

The sulphor comments make sense and a 200:1 dose was mentioned.

 

[Heckler]

The sulphor comments make sense and a 200:1 dose was mentioned.

Has anyone seen the price of 2T oil lately, and have they realised how much they are paying for red now?
Snake oil story, Ive read the German post and several others like it. Talk about smoother running etc, I repeat snake oil story!
Stu

 

[pampas]

Has anyone seen the price of 2T oil lately, and have they realised how much they are paying for red now?
Snake oil story, Ive read the German post and several others like it. Talk about smoother running etc, I repeat snake oil story!
Stu

I take it then that you have not tried it. certaily reduced to smoke at start up in my engine.

 

[fishermantwo]

I have been doing it for awhile. I use .5%, I have a two stoke outboard so have tw3 handy anyway. The fuel injector pump is what is being lubricated. Modern diesel is very dry, rub some between your fingers then try the same with Bio diesel, Bio diesel is very slippery by comparison. Diesel in this country is more expensive than petrol because its refined more for modern road cars. The old style marine diesels appreciate a slipperier diesel.

 

[Nostrodamus]

Non slippery diesel. Reminds me of another thread.

 

[Topcat47]

A friend who used to work for Ricardo in Shoreham tells me he's been doing this since bio diesel was added to mineral deisel at the pumps. He uses the cheapest 2-stroke oil and adds 1/2 litre to a full tank of fuel (~1%).

He says that it improves fuel economy, keeps the injectors clean and reduces particuates in the exhaust (he drives a Rover 75 deisel with around 150k miles on the clock). I'm a sceptic myself, however it seems worth a punt and I'm going to give it a go next but one fill up. I'll compare the range before and after and decide whether it's worth doing then.

 

[Quandary]

Adding 2 stroke oil to diesel

I tried it at our last but one fill up, mainly because I had two bottles left over after I change to a 4 stroke outboard, about 250ml. to 80 litres, did not notice any difference except a slight smell and the oily black stain which gradually appeared on the white hull near the exhaust; however, the fuel economy seemed to go up noticeably, from about 2 litres per hour to about 1.7 but that could be down as much to the light winds and flat seas for most of the trip. (Early July in W. Scotland) The engine is a 3 year old D1-30.

 

[Lakesailor]

a slight smell and the oily black stain

Seems about right.

 

[Heckler]

I tried it at our last but one fill up, mainly because I had two bottles left over after I change to a 4 stroke outboard, about 250ml. to 80 litres, did not notice any difference except a slight smell and the oily black stain which gradually appeared on the white hull near the exhaust; however, the fuel economy seemed to go up noticeably, from about 2 litres per hour to about 1.7 but that could be down as much to the light winds and flat seas for most of the trip. (Early July in W. Scotland) The engine is a 3 year old D1-30.

The heavier the fuel oil the bigger bang you get for your buck. One of the reasons that diesels are more economic than petrol engines.
A diesel will burn anything that can go thru the injectors, the heavier the oil, the more power it will produce. The governor keeps the revs constant and injects more or less as the revs try to go up or down. More power means the revs drop less which means the governor doesnt open up so less fuel consumed. However, the components of the pump and the injectors are protected by the fuel oil lubricicty (sic) so care has to be taken about what is put thru them.
Then one also has to think about the cost of the additive. Does the cost of the additive make the fuel more expensive in comparison to the savings in consumption? Plus what is the 2T? An oil, which is burned in the same manner as the fuel oil, no special properties to stop an engine smoking, especially in the minute percentages peeps talk about!
I stand by what I say, snake oil, expensive snake oil!
Stu

 

[vyv_cox]

There seem to be two arguments. One is that ULSD and older engines do not make ideal partners, whereas newer engines have had some sort of treatment that reduces wear in steel-on-steel components that were previously lubricated by the sulphur. 2-stroke oil apparently has a lower ash content than diesel fuel, so the 'oily residue' suggests that the oil was either a poor one or not 2-stroke at all. 2-stroke is very high in boundary lubricants, which seems to be exactly what is wanted here in non-hydrodynamic situations. The 'newer engines' bit seems to apply to automotive ones and I have no idea whether yacht engines are included.

The second argument, read on hundreds of 4-WD and other motoring enthusiast forums, is that adding the oil seems to make engines run and start better and makes them quieter. No science involved that I have found, but apparently thousands of user experiences.

'Refueler' who no longer posts here but does on the CA forums, suggests that adding a small volume of oil to tankfull of fuel can be beneficial for older engines, although AFAIR he didn't specifically mention 2-stroke.

 

[Quandary]

. 2-stroke oil apparently has a lower ash content than diesel fuel, so the 'oily residue' suggests that the oil was either a poor one or not 2-stroke at all.

You could be right, the oil was purchased from a yacht chandlers years ago as 2 stroke outboard oil in a fancy rectangular bottle when we had an Evinrude though it was branded 'Mercury' and I suspect they do not make oil. It worked fine in the outboard though and more recently has been used in the mix for the strimmer. Perhaps I should take some swabs off the hull for analysis?

 

[pappaecho]

In the good old days. fishermen used to put 5% of petrol into their diesel to act as an antiwaxing agent in sub zero conditions. I can fully understand that 5% petrol would dramatically reduce the lubricity of the fuel, increasing the wear on the injector pump. It would also have an adverse effect on the "diesel proof" flexible rubber piping. What effect does 2 Stroke oil have on the flexibles in a diesel installation?

 

[Monique]

In the good old days. fishermen used to put 5% of petrol into their diesel to act as an antiwaxing agent in sub zero conditions. I can fully understand that 5% petrol would dramatically reduce the lubricity of the fuel, increasing the wear on the injector pump. It would also have an adverse effect on the "diesel proof" flexible rubber piping. What effect does 2 Stroke oil have on the flexibles in a diesel installation?

I had a Golf II diesel in Canada. The only way to run it in winter is as above.

I use 2T oil to the tune of 1 liter in 250 of diesel. Volvo TMD 22... i.e. Perkins old design. OLD design .. Works nicely.

 

[vyv_cox]

In the 'good old days' red diesel had a sulphur content above 1000 ppm. ULSD has less than 10 ppm.

I assume 2-stroke oil to be very low in low-molecular weight compounds, so I doubt if its effect would be significant, especially in the 1:200 ratio (0.5%) that is suggested.

 

[Little Five]

There has been no mention of the effect of adding 2 stroke oil to diesel with regard to the longevity of the engine/and or the parts which should benefit from the addition. Is the debatable advantage only re fuel economy?